Art of and apparatus for generating and distributing music electrically.



I. CAHILL.

ART OF AND APPARATUS FOR GENERATING AND DISTRIBUTING MUSIC ELECTRICALLY APPLICATION FILED FEB. 17. 1904. RENEWED DEC. 14.1916.

1,213,803. Patented Jan. 23, 1917.

I4 SHEETSSHEET I- Invcnior.

, WM, pw W {0426 T. CAHILL.

ART OF AND APPARATUSI'OR GENERATING AND DISTRIBUTING MUSIC ELECTRICALLY.

APPLICATION FILED FEB. I7, I904- RENEWED DEC- I4 1916.

1,21 3,803. I Patented Jan. 23, 1917.

est L/ Invent'or. 27 1 I W zgle. WXW

T. CAHILL.

ART OF AND APPARATUS FOR GENERATING AND DISTRIBUTING MUSIC ELEGTRICALLY. APPLICATION FILED FEB. I7, 1904. RENEWED 05c. 14. me.

1 ,21 3,803. Patented Jan. 23, 1917.

I4 SHEETS-SHEET 3- IIIIII I III:-

. T. CAHILL.

ART OF AND APPARATUS FOR GENERATING AND DISTRIBUTING MUSIC ELECTRICALLY.

APPLICATION FILED FEB. I7. I904- RENEWED DEC-14.1916.

Patented Jan. 23, 1917.

14 SHEETSSHEET 4.

AXW

T. CAHILL.

ART OF AND APPARATUS FOR GENERATING AND DISTRIBUTING MUSIC ELECT'RICALLY.

APPLICATION FILED FEB. I7. I904. RENEWED DEC. I4. IBIS.

Patented Jan. 23, 1917.

IN VE/V TOR WITNESSES:

T. CAHILL. ART OF AND APPARATUS FOR GENERATING AND DISTRIBUTING MUSIC ELECTRICALLY. APPLICATION FILED FEB. I]. 1904- IIEIIEWED DEC. 14. I916- 1,213,803. Patented Jan.23,1917.

I4 SHEETS-SHEET 6- Attest Inventor.

T. CAHILL. ART OF AND APPARATUS FOR GENERATING AND DISTRIBUTING MUSIC ELECTRICALLY.

APPLICATION FILED FEB-17,1904. RENEWED DEC. I4. I9I6.

Patented Jan. 23, 1917.

14 SHEETSSHEET 7- Inventor.

I Attcsc:

l M W W.

T. CAHILL.

Patented J an. 23, 1917.

14 SHEETSSHEET 8- Trim ART OF AND APPARATUS FOR GENERATING AND DISTRIBUTING MUSIC ELECTRICALLY.

APPLICATION FILED FEB.17,T904- HENEWED DEC. 14.1916.

Attesc T. CAHILL.

ATING AND DIS ART OF AND APPARATUS FOR GENER TRIBUTING MUSIC ELECTRICALLY.

1904- RENEWED DEC. 14.1916- APPLICATION FILED FEB- 17 Patented Jan. 23, 1917.

14 SHEETS-SHEET 9.

Inventor.

T. CAHILL.

ART OF AND APPARATUS FOR GENERATING AND DISTRIBUTING MUSIC ELECTRXCALLY.

APPLICATION FILED FEB. 17, I904- RENEWED DEC. 14,1916.

Patented Jan. 23, 1917.

14 SHEETS-SHEET I0- Q3 $8 3 -$& $5 E Q AHQSC Inventor.

T. CAHILL. ART OF AND APPARATUS FOR GENERATING AND DISTRIBUTING MUSIC ELECTRICALLY.

APPLICATION FILED FEB. I7. I9U4- RENEWED DEC. 14.1916.

Patented Jan.23,1917..

I4 SHEETS-SHEET I I.

Attest T. CAHILL. ART OF AND APPARATUS FOR GENERATINGAND DISTRIBUTING MUSIC ELECTRICALL Y.

APPLICATION FILED EEK. II, I904- IIENEWED DEC. 14.19I6.

Patented Jan. 23, 1917.

I4 SHEETSSHEET I2- 7 Inventor.

Attesc:

T. CAHILL.

ART OF AND APPARATUS FOR GENERATING AND DiSTRIBUTING MUSIC ELECTRICALLY. APPLICATION FILED FEB. 17, 1904. RENEWED DEC. 14.1916.

1,213,803. Patented Jan. 23, 1917.

M SHEETS-SHEET 13- in case /7- 256 7 in (ass 17:362 7/ incasr 5 364 7' in case 5-362 7' in ems! L"- 198 T in case 6-210 7' W! TNESSES: IN V54 70/? y 7&7 em,

I. CAHILL.

ART 0F AND APPARATUS FOR GENERATING AND DISTRIBUTING MUSIC ELEGTRICALLY.

APPLICATION FILED FEB. 17, I904- IIENEWED DEC. I4. I916.

Afiast Envcrn'mr.

UNITED STATES PATENT OFFICE.

THADDEUS CAHILL, OF I-IOLYOKE, MASSACHUSETTS, ASSIGNOR, RY MESNE ASSIGN- MENTS, TO ELLIS SPEAR, E. HILTON JACKSON, GEORGE E. CAHILL, ARTHUR T. CAHILL, AND THADDEUS CAHILL, TRUSTEES.

ART AND APPARATUS FOR GENERATING AND DISTRIBUTING MUSIC ELECTRICALLY.

Specification of Letters ratent.

PatentedJ an. 23, 1917.

Continuation of application Serial No. 49,944, illed January 19, 1901. Divided and application died February 26, 1903, Serial No. 145,797. Renewed November 6, 1913, Serial No. 799,625. This application flied February 17, 1904, Serial No. 194,111. Renewed December 14, 1916. Serial No. 137,069.

To all whom it may concern: I

Be it known that I, THADDEUS CAHILL, a citizen of the United States, residing at Holyoke, Massachusetts, have invented certain new' and useful Improvements in the' disclosed in a prior allowable application of mine, No. 43,944, filed January 19, 1901; and most of the claims asserted herein, if not all of them, either were asserted in the same words or in substance in said original application, No. 43,944, or might, under the law and the practice of thePatent Oflice, have been so amerted in said original application. In so far as the subject matter of the resent application is identical with the su 'ect matter of said original application, llo. 43,944, filed January 19, 1901, this application is a continuation of said original application No. 43,944.

In Letters Patent of the United States to 1ne No. 580,035, dated April 6, 1897, is .described an art of and apparatus for generating and distributing music electrically.

My present invention consists in certain improvements in that art and in the apparatus for practising the same, which are hereinafter described, by means of which improvements certain new and useful efi'ects are produced, which have never, so far as I am aware, been produced before.

And, without attempting in this introductory ortion of the specification any definition o the invention or any statement of claim, for which the reader is referred to the statement of claim at the end hereof,'I would say, briefly and informally and byway of introductory explanation, that my present apparatus, hereinafter described, difiors from the apparatus illustrated anddescribed in the specification and drawings accompanyin the Letters Patent aforesaid, in the f0 lowing, among other particulars, namely;

First. In the apparatus illustrated in the drawings accompanying the specification of the Letters Patent aforesaid, a set of pitchshafts is employed, corresponding respectively to the notes of a musical Scale within the compass of an octave (twelve for the chromatic scale of equal temperament),each of said shafts giving movement to rotary vibration-generating devices for producing electrical vibrations correspondinfg to the successive octaves of that note 0 the scale to which such shaft corresponds, each of these shafts being connected by a belt of its own with a common driving-shaft from which they all receive movement. 'With this arrangement, the several octaves of a note were necessarily in tune with each other, for the rotary devices by which the'electrical vibrations corresponding to them were produced were carried by the same shaft; but the vibration-generating devices corresfponding to notes that were not octaves 0 each other were carried by different shafts and were liable on account of variations in the amounts of slip of the belts driving them to get out of tune, from time to time, more or less, thereby necessitating care and attention. In the specification aforesaid, the possibility of usin toothed gearing for the pitch-shafts,there y to avoid slip, was referred to. But no toothed gearing was illustrated in the drawings or described in the specification, for none suitable for the urpose had been contrived at that time. ut a toothed gearing is illustrated in the accom anying drawing, b which all the pitch sha s are so connecte together that it is impossible for the notes to get out of tune with one another; and everything is contrived in such a manner that the most pertrical waves, as produced in the .first instance by the vibration-generating devices,

. varied more orless widely from the sinescribed, having a 1n vibration by. a plurality. of small electroform and were then assimilated, in a greater or less degree, to the sine-form by successive inductive transfers, tone-purifying devices being used for-that purpose. By my present invention, I preferably generate electrical waves that are nearly sinusoidal or at all events, that are so nearly free from the higher and harsher odd-numbered harmonics (orpartial-tcnes) that they may be used for producing music electrically, without requiring the use of devices that serve merely or solely for tone-purifying. I

Third. In the Letters Patent aforesaid, a form of vibration-translating device is dewooden sound-board, set

magnets, receiving vibratory electrical currents from vibration generating devices. By my present invention, I use, preferably, as a. vibration-translating device, in combination with the other parts of the apparatus, an electrically-vibrated diaphragm, preferably of soft iron .or soft steel (in effect, a receiving telephone) in combination with a her; This form of vibration-translating device, particularly if the diaphragm be made as I have been making them) of soft iron or steel, is quite free from alteration by the weather and produces sounds of a better quality andof greater power and through Wider range of pitch, and with less electrical energy than is required by the kind of vibration-translating device illustrated and described in the Letters Patent hereinbeiicre enumerated; and seems also more satisfactory in other particulars. llfourthln the apparatus hereinafter described, I provide independent or parallel circuits for the exciting coils of the several alternators and also I provide means for alter ng the intensity of excitation of the several alternators, each independently of the others. Thereby I make it possible to easily voice the instrument, so as to transmit over the mains the several series of vibrations, each with the power required; and make it possible-also to compensate, in a measure, the tendency of the lines to transmit and of the diaphragms to produce some tones less strongly than others, I

I consider it convenient to use in same apparatus all the improvements above referred to, I wish it to be clearly understocd at the outsetthat one or more of those improvements may beused and the others not used or a portion of them may be used one form of apparatus and another portion used in another and difierent form of apparatus.

For-greater convenience, I shall first dcscribe, with reference to the accompanying drawings, one form of apparatus for em cm or other suitable reinforcing air-chambodying my invention 'and b means of which 1t may be practised. A ter that one form has been made clear-,1 shall describe some of the more important of the many 'alterations and modifications that may be made. a y

In the accompanying drawings Figures 1 to 17 illustrate the form of appal atus that I shall first describe; while Figs. 18 to 37 illustrate some of the many possible modifications or alternative constructions. Fig. 1 is a schematic view, illustrating the'electri cal connections. Fig. 2'is'a schematic view, partly in section, partly in elevation, showing a key of a keyboard and a circuit-closing device controlled-by that key and serving, when that key is depressed, to throw the vibrations of the corresponding alternator upon the line. Fi 3 is a sectional view in elevation, illustrating'one of my vibrationtranslating devices. Fig. is a detail view Similar to Fig. 3, but on a larger scale; the most of the reinforcin horn being broken away. Fig. 5 is a detail, a planview, on a larger scale. than Fig. 4; the reinforcing horn, mouth-piece and diaphragm being removed. Fig. 6 is a view'in general similar to Fig. 4, but illustrating a construction in which an electro-magnet, excited by a local battery, is used in place of the permanent magnet, illustrated in Fig. Fig. 7 is a plan view, largely schematic, illustrating one of the arrangements of gearing that I have contrived for driving the twelvepitchof the twelve pitch-shafts, shown in Fig. 7

with the alternators to which it gives movement. F i 9 is a detail sectional view in elevation, illustrating one shape of inductor tooth (out of many possible shapes) that may be used. Fi 10, is a view similar to Fig. 8, but on a larger scale, and with the rotating parts in sections. Figs. 11, 12, 13, 14, 15, 16 and 17 are detail sectional views, partly in elevation, on the lines 11, 11; l2, 12; 13, 13; M,- ll; 15, 15; l6, l6; and 17, 17; respectively, Fig. 8, illustrating the characteristic difi'erences of the several al-' ternators respectively that are carried by a pitch-shaft, corresponding respectively to the successive octaves of that note of the scale to which such shaft corresponds and constructed to produce respectively 3, 6,

'12, 24, 48, 96, and 192 cycles or complete electrical vibrations for each revolution of the pitch-shaft carrying them. in Figs. 11 and 12, the armatures and the exciting winding of the field-maggots 24, 2e and 2,5, 25, are omitted; and in i gs. 15, 16 and 1? much of each alternator is broken away. Fig. 12 is a detail view in sectional elevation and somewhat similar to Fig. 12, but illustrat- 1w ing the armature coils, and their supporting devices, which are omitted from Fig. 12. In Fig. 12, some of the parts are removed to expose others to view. Fig. 12, is a detail section on the line 12 12, Fig. 12". Figs. 18 and 19 illustrate a modified arrangement of the' alternators; Figs. 20 to 33 inclusive, are schematic views, illustrating modified or alternative arrangements of the gearing, for the alternators, adapted to the chromatic scale of equal temperament. Figs. 34, 35, 36 and 37 illustrate different arrangements of the gearing for thealternators, adapted to the diatonic scale of the natural or just intonation.

I have spoken of several of the figures above described as schematic views or as in part schematic. By a schematic view I mean a view illustrating certain .essential features of a device, apparatus or arrangement of parts, in which, in order to illustrate the essential features more clearly, no effort is made to show the true sizes, proportions, relative distances and positions of the parts, or indeed, in many cases, their form. Such views are especially necessary in illus trating electrical circuits and apparatus. In most of the schematic views, if not in all, a few things of a kind are in some cases shown inillustration of all the things of that kind, for an attempt to illustrate all those things in one view would be impracticable, if not impossible. and would tend to obscure the clearness of the drawing.

In many of the views, whether schematic or geometric, a greater or less portion of the apparatus is broken away, as the breakines indicate, or in some cases is omitted. Further, I have not endeavored to illustrate or describe all the minute details of construction of things old and well known, such for example, as alternator-s, inductoriums, switchesand keyboard mechanisms, etc., but I have clearly illustrated and fully described those features of construction that are new with me and essential to the carrying out of the invention.

The schematic drawings, as before said, are of course not made to scale, and in the drawings that are made to scale different scales are of necessity used for different figures; but all that is new with me and essential to the invention is so clearly illustrated and so fully described that persons skilled in that part of the electrical art which relates to alternating currents and alternating current machinery and apparatus, can make a working machine from the information contained in this specification and in the accompanying 'drawi n gs.

In the system illustrated in Figs. 1 to 17, which I shall first describe. there is a set of alternator-s, having vibration-frequencies corresponding respectively to the vibrationfrequencies of the notes of a musical scale,

through a sufiicient range. Seven octaves, lacking one half-tone, are illustrated in the drawings, though, of course, a greater or less compass may be used, if desired.

In most of the drawings, I have illustrated, this electrical system as adapted to.

the chromatic scale of equal temperament, which is now used almost universally throughout christendom; but it is to be understood that my invention is applicable also to other. scales and temperaments. For the chromatic scale of equal temperament, then we have, or at least may have as illustrated in the drawings, 12 shafts, 1, 1", 1, 1, 1", 1, 1 1", 1, 1 1, 1', corresponding respectively to the twelve consecutive notes of the chromatic scale (as C, C-sharp or D-fiat. D, D- sharpv or E-fiat, E, F, F-sharp or G-fiat, G, G-sharp or A-fiat, A, A-sharp or B-fiat, and B,) and each carrying or giving movement to the alternators that serve to produce the successive octaves of the note to which such shaft corresponds and for which it serves. For convenience, we may term these shafts 1*, 1'., etc., pitch-shafts. I

With the exact arrangement of parts illustrated in the drawings, and whicli it is to be understood, may be varied from, more or less required, each pitch-shaft gives movement to seven alternator-s, 2, 2, having vibration-frequencies corresponding respectively to the vibrationfrcquencies of successive octaves of the note for which the pitchshaft carrying them stands. 'aIf the lowest in pitch of these alternators has a frequency of 11. cycles per second, the other alternators,

'in the ascending, scale, must have frequencies of 212,411, 8n, 16a, 32a, and Gin, respectively; if the lowest of these alternators, 2, 2. produces, for example, 3 cycles or complete toand-fro electrical vibrations per revolution, as illustrated in the drawings, the other alternators, carried by the same pitch-shaft,

will produce, respectively 6, 12, 24. 48, 96, and 192 cycles or complete toeand-fro electrical vibrations for each revolution of such shaft.

' The twelve pitch-shafts 1, 1",- 1", '1", 1, 1', 1 1, 1, 1, 1, and 1', with the sets of alternator-s carried by them, may be made to be exactly alike; that is, the alternators carried by any one of the twelve pitch-shafts may be'in every respect exactly like the corresponding alternators carried by the other pitch-shafts; and for the sake of convenience of explanation (and for that reason only,) we shall first assume this exact simi larity; in which case, to make the twelve pitch-shafts correspond respectivelv to the twelve notes of the chromatic scale, we drive those shafts with angular velocities corresponding respectively to the vibrationfrequencies of the twelve. notes of the chromatic scale. And when thus; driven, the alternators carried by one of the twelve pitchshafts will give the note in its successive octaves; the alternators carried by another pitch-shaft will give the note C-sharp or D- flat of equal temperament in its successive octaves, while the other ten shafts will give each the successive octaves of the .note of the chromatic scaleto which such shaft corresponds.

0f the gearing for the pitch-skafts. One form of gearing that I have contrived for this pur ose, is illustrated schematically in Fig. in which 1, 1', 1, 1, 1", 1,

- 1 1 1, 1, 1, and 1", are as before said, the twelve pitch-shafts, corresponding. re-

spectively to the twelve consecutive notes of the chromatic scale and each giving movement to the alternators that serve to produce the successive octaves of that note of the chromatic scale to which such pitch-shaft corresponds. Each of these pitch-shafts is mounted in suitable bearings, (preferably I self-alining bearings with ring oilers) 5, 5,

supported by the pedestals. 6, 6, that rise from the bed plate 7, 7.- This bed-plate at least in the caseof large machines, is preferably made of a plurality of sections, as

" 7,.7, supported on masonry and firmly bolted I three consecutive notes 0' together. The bed-plate 7, 7, the bearings ;5, 5, and the pedestals 6, 6, form no part of my invention and are not illustrated in detail in the drawings. They appear to some extent in Figs. 8, v9, and 10, but the bearings and pedestals are entirely omitted from Fig. 7 and the otherFigs. 20 to 33 which illustrate different arrangements of the gearing; and the bed-plate is omitted from most,

of these figures: and in all these figures the alternators carried by a pitch-shaft and which are clearly shown, so far as is essential to my invention, in Figs. 8 to 17 indrive said shaft 8; for which purpose the electrical motor, 11, may be used, with its armature mounted on and keyed to said shaft; or any other motor or driving mechanism whatever that is suitable for the purpose may be used. In Fig. 7, asalso in all the other figures that illustrate modifications of the gearing, a reference numeral consistmg of figures followed by the letter", indicates a gear-wheel having as many teeth as the number indicated by such figures. Thus 89', applied as a reference numeral to a part, indicates that it is a gear-wheel having eightym'ine-teeth; 84!, a gear-wheel with 84 teeth; 37 and 44 respectively, gearwheels of 37 teeth and 44 teeth, respectively, and so on. I

The twelve itch-shafts 1 1", &c. are arranged as be ore said, in our ,grou s of three shafts each, the three shafts 0 each group correspondin to three consecutive notes of the chromatic scale. The first group consists of the shafts 131", and 1; the second of the shafts 1, 1, and l; the third of the shafts 1 1 and 1; and the fourth group of the shafts 1 1, and 1*. And in each of these groups, the lowest shaft (in'pitch) of the group (the shaft 1, in the first group; 1 in the second; 1 in the third; and 1 in the fourth group) is connected with the middle shaft of its group, (l -in the first I group; 1, in the second; 1 in the third; and 1 in the fourth group) bya gear 89 having 89- teeth, keyed fast to said lowest shaft a and meshing with a gear 84' having 84 teeth, keyed fast to the middle shaft of the same group; and the middle shaft of each group (1?,1, 1 or 1 as aforesaid) is connected with the highest shaft (in pitch) of its group, (the shaft 1*, for the first group; 1, for the second; 1 for the third and 1', for the fourth group) by a gear 89 having 89 teeth,- keyed fast to said middle shaft and meshing with a gear 84 having 84 teeth, keyed fast to the highest shaft of the same group.

The shafts 1, 1", and 1, constituting the first group are driven by means of a gear 88 keyed fast to the shaft 1', having 88 teeth, and meshing with the gear wheel 9 that is keyed to the shaft 8; while the shafts- 1 1 and'l, constituting the second group, are driven by means of a gear 74 having it teeth, .keyed fast to the shaft 1* and also meshing with the gear wheel 9. But the third group. of shaftsfi 1 and 1) and the fourth group (1, l and 1") respectively, are driven by the wheel 10 keyed to the shaft 8 and meshing with the gear 88 of 88 teeth, keyed fast to the shaft 1" and the gear 74 of 74 teeth, geared fast to the shaft 1. Supposing the alternators carried by each of the twelve pitch-shafts 1, 1 1, 1, 1, 1, 1 1, 1 1 nd 1 to be like (and in'particular to produce the same numbers of cycles per revolution as) the corresponding alternators on each of the other pitchshafts (in which case the only differences between the said twelve pitch-shafts, by which they'are made to correspond respectively to twelve notes of the chromatic scale, consist .in the different angular velocities with which they are respectively driven, a condition of things which we shall term-Case A, to distinguish it from the'other cases hereinafter explained) the wheels 9 and 10 may have respectively 128 and 18 1 teeth, or an equal multiples thereof, as 256 and 362 teeth respectively. And if the shaft 8 be driven with a speed of 233 revolutions per minute, the 12 pitch-shafts, 1*, 1",-1, 1, 1, 1, 1 1 1, 1 1', and 1", will correspond respectively to the 12 consecutive notes of the chromatic scale founded on c; which makes the lowest note of the series of alternators before described the c ((3 of 32 vibrations per second, (which is the lowest 0 of the pianoforte,) and the highest note, or at least the highest ground-tone, the 5, seven octaves iacking one half tone above the 0 last mentioned. If the speed of the shaft 8 be altered. the pitches of all the notes will be altered together, in exactly the same proportions. The builder or user can drive the machine at Whatever speed, within its safe mi-king limits, may best suit his purposes,

and at whatever speed the shaft 8 may be driven, the twelve shafts 1, 1", 1, 1", 1, 1 1 1, 1 1, and 1" will, as before said, correspond respectively to the 12 consecutive notes of the chromatic scale; and the alternators 2, 2, (Figs. 8 to 17 carried by each such shaft, will produce thesuccessive octaves of that note of the chromatic scale to which the pitch shaft carrying them corresponds.

Any variation in the angular velocity of the series of shafts will produce, as before said. a corresponding alteration in the pitch of all, but the relative pitches of the various alternators will remain fixed and'unchangeable; for all the twelve shafts 1. 1", &c. are geared together in such a manner that no change can be made in the angular velocitv ,I am aware in any commercially useful or musically meritorious musical instrument.

Numerous alterations may be made in the arran ement of the shafts and gearing without departing from certain of the essentiol principles. combinations or su combinations belong ng to my invention. Some of these alterations and modifications will be descri ed hereinafter.

0f the altermztom.-We have already stated the relative vibration-frequencies of the various alternators 2, 2. Any kind of alternator whatever that is suitable for the purpose may be used. But Whatever kind of alternator be used. it is important that the successive cycles of any given alternator that of every other wave. For if the succes-' This fixed and unchangeable sive cycles of an alternator have materially unequal periodic times or if it generate simultaneously in its several armature coils, waves of unequal periodic times (which will happen if the pole pieces of such alternators as those illustrated in Figs. 11 and 12 or the teeth of the revolving inductors illustrated in Figs. 13 to 17 be unequally spaced) the effect upon the purity of the notes and especially upon the chords is liable to be disas trons. Inequalities may perhaps exist, so minute as not to be sensibly prejudicial, and possibly some special effects mightbe produced in special cases of inequalities (I ailirm nothing on that point); but at least for all ordinary purposes, it is, according to my experience, a safe rule to make the pole pieces 24, 24, and 25, 25 in Figs. 8, 10, 11 and 12 as nearly as is conveniently possible of equal sizes and disposed equi-distant one from another. So also, while the different indicators illustrated in Figs. 8, 9, and 10, and 13 to 17 have preferably teeth of different sizes, each inductor, should in my judgment, to secure the best effect, have all its teeth as nearly as is conveniently possible of exactly equal size and exactly equi' distant one from another. have cut the teeth of. the inductors that I have used in a large and carefully built gear-cutting machine, provided with a-very accurate indexing mechanism, and in particular having a large and very accurate worm-wheel and Worm.

As I have bef re said, any form of alternator whatever that is suitable for the pur- To this, end I pose may be used. But for divers practical steel castings or iron or steel forgings) to which the iron or steel pole-pieces 24, 24, belonging to the lowest or leftm st alternator, (Figs. 8 and 10) and 25. 25 belonging to the second alternator, Figs. 8v and 10, are suitably attached, as for example *by the nuts 26, 26, and washers 26, 26". The'pole pieces 24, carried by the disk 21, are exactly opposite the corresponding pole-pieces 24, carried by the disk 22; and the pole-pieces 25 carried by the disk 23 are exactly opposite the corresponding pole-pieces 25 carried by the disk 22. Exciting coils 27, 27, are wound upon the pole-pieces 24, 24 and similar coils 28. 28 are wound upon the polepieces 25, 25. The coils 27 27, are connected together in series or in parallel (preferably in series) and have their opposite terminals connected to the insulated contact rings 29,

29,. upon which the brushes 30, 30 bear, which'are connected through arheostat 12, Fig. 8, with the opposite poles of a direct current dynamo 31, or other suitable electric source. The exciting coils28, 28, have their 0p osite terminals connected to similar insu ated contact rin s 29, 29, upon which other brushes bear, t at are connected through a similar rheostat, 12, with the oposite poles of the exciting dynamo 31, beore mentioned. In the air gapor space between the poles 24, 24, and 25, 25, lie the ar mature coils 32, 32, made preferably of insulated copper ribbon or strip, wound uponcores 32, 32, of vulcanite or other suitable insulating material. To ive greater strength and stiffness tothe code 32, 32, the

. copper ribbon or strip out of which they are wound, and the external surface of the cores upon which they are wound, are preferably a little curved, as illustrated, for example, in section in Fig. 12 And to prevent the. ribbon out "of which the coil is wound from unwinding, the coil may be securely wrapped with binding wire at 32", .as illus-' trated in Fig. 12*, the binding wire being well insulated from the coil about which it is wrapped and'heing soldered together in the usual manner, to prevent it from unwrapping. Each of the coils 32 is firmly attached by a seental clamp 33, to the stifil linedring 35; a bolt 34, passing through said clamp 33 and the core 32*, and ring 35, with a tightening nut34, by which the coil 32 is locked firmly in place. Pieces of hard fiber or other suitable insulating material,-

32, and 32 (Figs. 12 and 12 are interposed between the coil 32 and the segmental clamp 33 and ring 35 respectively. The seental clamp 33 is provided with two ears or lugs 33, 33, to engage the outer surface of the ring 35, and these lugs, with the bolt 34, hold the clamp 33 in place, The laceoi the ring 35 and these lugs, with the bolt 34, hold the clamp 33 in place. The

ring 35 is preferably made of bronze, German silver or othernon-magnetic material and is firmly bolted to the cast iron ioot35 which is. in turn bolted to the bedplate 7.

.- The exciting coils 27 and 28 are wound in such a manner (a) that each of the poles 24, 25, on the disks 21 and 23 is of opposite polarity to .the pole facing it on the disk 22, (b) that, advancing circumferentially, the successive poles 24, 24, are alternately of opposite polarity, while (a) allthe pole-pieces 25 carried by the disk 22 are of one polarity and all the pole-pieces carriedby the disk 23 are ofthe opposite polarity. In the drawings' Figs. 8, 11, and 12, the difiering'nolarities are indicated by theletters N, signifynorth pole, and S, signifying south pole.

The purpose and the result of the arrangement described is that with every revolution of the pitchshaft carrying them, the six pairs of pole-pieces 24, 24 belonging to the leftmost alternator Figs. 8, and 10, produce three cycles or complete electrical vibrations, in the armature coils, 32, 32 that lie in the gap between said pole-pieces 24, 24, while the six pairs of pole-pieces 25, 25, belonging to the next adjacent alternator, produce just twice as many electrical vibrations per revolution in the armature coils 32, 32, that lie in the gap between said pole-pieces, 25, 25.

The armature-coils 32, 32, that lie in the gap between the pole-pieces 24, 24, are connected together into one series in such a manner, according to the known rules of the electrical art; that the voltage in one reinforces the voltage in another.

The general type-of alternator just demiddle as well as the higher compass, alternators having rotating iron armatures or in- .ductors.

Figs. 8 to 13 and 13 to 1? illustrate one errangeinent of inductor alternators ior giving the higher octaves of the notes produced by the bass-generators, illustrated to the left of FigsS and 10 and in Figs. 11, and 12 and. already described. In each of these indnctor-alternators there is (a) a rotating inductor 36, formed of thin plates of soft iron or steel, suitably insulated from each other,

bolted together between the stifiening side plates 3'3, 3? and lieyed to the shalt l, or

l etc., to rotate therewith; (h) a plnrahty of field poles 38, 38 of alternate north and south polarity, each having an exciting winding 39 wound about it, and a plurality of armature coils 40, 40, wound in slots formed in the polar face of the field pole, in immediate proximity to the rotating inductor 36; and (c) a suitable frame 43, pref erably of annular internal shape, to which the pole-pieces 38, 38 are secured by the L- shaped keys 44, 44, shown in the drawings, or in any other suitable manner.

The stiifening side plates 37, 37, are separated from the iron or steel plates of the.

inductor 36. by, annular plates or rings 37,

37, of German fsilver' or; other suitable non-magnetic material, to prevent or reduce to "a minimum the production of Foucault. or

eddy'c'u'rrents in said plates-37, 37. Topre vent the production of such currents in the r shaft 1'. '1", etc. a sleeve of-German silver i 37", is'interpo sedfbetween said shaft and. 9 

